Field of the Invention
The invention relates to an interface for transferring signals from a hand-operated signal generator to a data processing device, the hand-operated signal generator being capable of delivering at least two types of signals for moving an image on a display associated with the data processing device in at least two different ways, in which each type of signal corresponds with at least one specific mode of operation of the signal generator associated with said type of signal.
The invention furthermore relates to a method of transferring signals from a hand-operated signal generator to a data processing device, the hand-operated signal generator being capable of delivering at least two types of signals for moving an image on a display associated with the data processing device in at least two different ways, in which each type of signal corresponds with at least one specific mode of operation of the hand-operated signal generator associated with said type of signal.
Such an interface and method are known from U.S. Pat. No. 5,565,891. This patent discloses a hand-operated signal generator which is capable of delivering three rotation signals and three translation signals. The three rotation signals relate to rotations in mutually perpendicular directions and the three translation signals relate to three translations likewise in mutually perpendicular directions. In fact, this patent describes a hand-operated signal generator which makes it possible to have an image on a display undergo three translations in mutually perpendicular directions and three rotations in mutually perpendicular directions, or, in other words, a movement comprising six degrees of freedom. This is also referred to as the manipulation of 3D objects with six degrees of freedom.
Such hand-operated signal generators for manipulating 3D objects with six degrees of freedom are not easy to operate and require a long period of practice before an operator has acquired sufficient skill to carry out a desired rotation, translation or a combination of rotational and translational movement with the desired precision by means of the hand-operated signal generator.
Research carried out at the University of Toronto has shown that many people, when manipulating 3D objects on their display, prefer carrying out one type of movement, such as a rotation, first and then another type of movement, such as a translation, in order to thus effect the desired manipulation. Very few people carry out a manipulation consisting of a combination of rotational and translational movement in one operation.
Furthermore it takes a considerable amount of practice before one is able to control the hand-operated signal generator in such a manner that only one type of signal, for example, only rotation or only translation, is delivered. Generally, a desired rotation will, for example, be accompanied by a translation signal of a certain magnitude, and vice versa. For example, when using the device disclosed in the aforesaid U.S. Pat. No. 5,565,891, it will take a considerable amount of practice to prevent a rotation about an axis of rotation being accompanied by a translation along an axis extending perpendicularly to the axis of rotation. Depending on the pressure that is to be exerted on the spherical element disclosed in U.S. Pat. No. 5,565,891 in order to effect a rotation about an axis in the plane of the device, said pressure will also result in a small, albeit not negligible, signal indicating an undesired translation in a direction perpendicular to the plane of the device.